This invention relates to improvements in two-cycle internal combustion engines and, more particularly, to such engines having improved fuel efficiency.
In conventional two-cycle, internal combustion engines, with precompression in the crankcase, scavenging of exhaust gases is generally realized using fresh carbureted air, leading undesirably to high exhaust losses. It is well known that as a result such engines have high fuel comsumption and the presence of unburned hydrocarbons in the exhaust gases.
Numerous techniques and devices have already been proposed and are used to improve conventional two-cycle engines by remedying the above-mentioned drawbacks. The heretofor provided devices generally aim at scavenging the burned gases by pure air and introducing the carbureted air only after scavenging. This is the case, for example, of direct injection engines for which the scavenging air produces an aerodynamic screen across the injector. It has also been proposed to use an auxilliary compressor making it possible to assure scavenging with pure air and to assure producing an aerodynamic screen.